Exhaust gas treatment systems for internal combustion engines, including but not limited to gasoline engines or diesel engines, may include a catalytic converter for treating a flow of exhaust gas from the internal combustion engine. The catalytic converter is a flow through device that consists of a housing containing a monolith, such as but not limited to a honeycomb-like structure. The monolith includes a large surface area that is coated with an active catalyst layer. The active catalyst layer may include, but is not limited to, a Platinum Group Metal (PGM). As the exhaust gases traverse the active catalyst layer, carbon monoxide, gaseous hydrocarbons and liquid hydrocarbon particles, i.e., unburned fuel and/or oil, are oxidized, thereby reducing harmful emissions.
The housing of the catalytic converter includes an inlet and an outlet, and typically includes a tubular shape defining an interior space that is larger than a flow area of the exhaust pipes connected to the inlet and the outlet respectively. Accordingly, the housing of the catalytic converter includes a conical section adjacent each of the inlet and the outlet to transition from the smaller diameter of the exhaust pipes to the larger diameter of the interior space of the housing. The more evenly the flow of exhaust gas is distributed across the monolith, the more efficient the catalytic converter operates.